Along with house dust mites, allergies due to cockroach allergens are also a serious problem in the USA and Canada. Kang & Sulit (1978) carried out allergy skin tests in Illinois with cockroach antigen along with various common inhalant allergens on 222 atopic and on 63 non-atopic subjects. The most prevalent allergen producing a positive skin test was house dust mite antigen with a positive response of 72%, 78% and 57% in atopic adults, atopic children and non-atopic children, respectively. The next prevalent positive skin test was to cockroach antigen with 50%, 60% and 27%, respectively, of the three groups tested. Incidence of cockroach hypersensitivity was 58% among asthmatic adults and 69% among asthmatic children. The results indicate that cockroach hypersensitivity is very prevalent and that cockroach antigen is an independent agent from house dust mites as a cause of immediate hypersensitivity reaction.

A number of studies have established that cockroaches are an important and independent risk factor for allergic asthma, particularly among urban, inner city, Afro-American or Hispanic populations in the USA. The frequency of allergy to cockroaches in asthmatic patients of these populations is around 50% and is related to indoor exposure to cockroach allergens (Rosenstreich et al., 1997). Sarpong et al. (1996) observed that because cockroach populations are highest in crowded urban areas, it has been suggested that the increased asthma morbidity and mortality rates in inner cities could be related in part to cockroach allergen exposure; they examined cockroach allergen exposure in the homes of children with asthma in both urban and suburban locations and related the rates of exposure and sensitization to socioeconomic, racial and demographic factors.